Add nfit_test support for DSM functions "Get Security State",
"Set Passphrase", "Disable Passphrase", "Unlock Unit", "Freeze Lock",
and "Secure Erase" for the fake DIMMs.

Also adding a sysfs knob in order to put the DIMMs in "locked" state. The
order of testing DIMM unlocking would be.
1a. Disable DIMM X.
1b. Set Passphrase to DIMM X.
2. Write to
/sys/devices/platform/nfit_test.0/nfit_test_dimm/test_dimmX/lock_dimm
3. Renable DIMM X
4. Check DIMM X state via sysfs "security" attribute for nmemX.
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>